How do you manage your tapes?

Having enough tape for all your DB backups can be tricky.

One of the big problems in any data initiative is having enough tape to store your backups offsite.  Now, it seems a little dated doesn't it?  I mean, pushing backups to tape in late 2010?  And unfortunately even though tapes are expensive and volatile, there really isn't a much better solution to getting your backups offsite yet.  So the problem comes up time and time again;  How do you get enough tape space to store everything you need to?

One method you can use (we're mainly talking about DB backups here) is to compress all of your backups so they take up less tape space.  And depending on your RDBMS you'll have varying degrees of success with that.  It's not always feasible to compress backups though.  Sometimes the software's just too expensive and while it may be cheaper than the extra tapes to store the uncompressed versions, I find that few companies care about those longterm numbers.

Another solution is to take smarter backups of your read-only DBs.  Backing up read-only DBs every day and pushing them to tape is just a waste of every resource involved.  You may be stuck though unless you're willing to keep meticulous records on which backups are on which tapes.  And you have to also make sure there's not a backup on an old tape that you're about to retire too.  This can be a solution, but it takes a special kind of company to have the stomach for that kind of record keeping.  So to avoid that kind of record keeping it's best to take periodic backups of your read-only DBs just to make sure they'll still be good and you can find them reasonably.  So you could take a backup and push them to tape say once a month, so you know that the last day of every month has the read-only DBs on it. 

That's not an outstanding solution either though.  Oh sure, it sounds good on paper, but when you go to practice it, it isn't as shiny.  The problem is that you're trying to save tape space by not having the read-only DB backups on it every day.  But if you're going to have it at the end of every month, then you have to reserve the space so it'll fit.  So while you've saved all that space on the tape, you're not allowed to use it or you won't be able to take your end of month backup. 

Maybe the solution is to keep a set of tapes dedicated to read-only backups.  This way you can just overwrite them every month and you're golden.  This will increase your cost though because with all the constant overwriting the tapes will wear out more than the others and will have to be replaced faster if you want to ensure they'll work for you.

Of all of these possible solutions, the one I've found the most compelling is compressing the backups.  This really goes the furthest to reducing the tape footprint.  And maybe you can devise something else for your read-only DBs.  Maybe just back them up to disk once a week or so and never push them to tape.  I have been in a few shops though where they rely on their RAID level to provide their longterm backups for certain DBs.  These would be like your read-only DBs where you're not really concerned with having to recover transactions.  I've never seen how these solutions work over say a 10yr period, but for the 2-3yrs I was there they worked just fine.  And I'd say that a disk with RAID is going to be more reliable than most tapes for longterm storage.

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